Hadith 4:405

Narrated Al-Amash:

I asked Abu Wail, "Did you take part in the battle of Siffin?" He
said, 'Yes, and I heard Sahl bin Hunaif (when he was blamed for lack
of zeal for fighting) saying, "You'd better blame your wrong opinions.
I wish you had seen me on the day of Abu Jandal. If I had the courage
to disobey the Prophet's orders, I would have done so. We had kept out
swords on our necks and shoulders, for a thing which frightened us.
And we did so, we found it easier for us, except in the case of the
above battle (of ours).' "